1. Field of the Invention
The present invention relates to a power module suitable for driving a switched reluctance motor (which will be hereinafter referred to as an xe2x80x9cSRxe2x80x9d motor).
2. Description of the Background Art
FIG. 10 is a circuit diagram showing a circuit structure of a conventional power module for driving an induction motor, a DC motor or the like. In the power module, three series circuits are connected in parallel with one another between a P power wiring 85 for transmitting a high potential side power potential and an N power wiring 86 for transmitting a low potential side power potential, each of the series circuits having two switching elements 81 connected in series. For example, an IGBT is used for the switching element 81.
Each series circuit is further provided with a diode element 82 connected to each switching element 81 in antiparallel. The xe2x80x9cantiparallel connectionxe2x80x9d implies such a parallel connection that a direction of a main current flowing in the switching element 81 is reverse to that of a forward current flowing in the diode element 82. Consequently, the diode element 82 functions as a flywheel diode for preventing the switching element 81 from being damaged by a backward current.
An output terminal 83, 84 or 85 is connected to a connecting portion of the two switching elements 81 belonging to the series circuit. Six switching elements 81 are selectively turned on and off out of phase so that outputs having three phases, that is, U, V and W phases are fetched from the output terminals 83, 84 and 85, respectively. Accordingly, the induction motor or the like can be driven through a connection of the output terminals 83, 84 and 85 to three-phase inputs of the induction motor or the like, respectively.
In recent years, the SR motor different from a conventional induction motor or DC motor has appeared. However, a special connecting system for driving the SR motor is required and the power module shown in FIG. 10 cannot be used. For this reason, each of a switching element and a diode element as discrete elements or a combination of conventional power modules has been employed as a driving device for driving the SR motor. As a result, there has been a problem in that the driving device is large-sized and is lacking in versatility and a manufacturing cost is increased. Consequently, the spread of the SR motor is obstructed.
In order to eliminate the above-mentioned problems of the conventional art, it is an object of the present invention to provide a power module capable of driving the SR motor, giving a small size and high versatility and reducing the manufacturing cost.
A first aspect of the present invention is directed to a power module comprising a substrate, first and second power wirings provided over the substrate, first to Nth (Nxe2x89xa72) terminal pairs provided on the substrate, each pair thereof having first and second output terminals, and first to Nth circuits provided over the substrate, each circuit thereof being connected to the first and second power wirings, the nth circuit including, for all n (n=1 to N), a first series circuit having a first switching element connected to the first power wiring and a first diode element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the first output terminal of the nth terminal pair, and a second series circuit having a second diode element connected to the first power wiring and a second switching element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the second output terminal of the nth terminal pair, wherein the first to Nth circuits are arranged in this order, all of switching elements and diode elements connected to the first power wiring are arranged to form a first line, all of switching elements and diode elements connected to the second power wiring are arranged to form a second line aligned with the first line, the switching elements and the diode elements are arranged alternately in all of directions along the first line, along the second line and crossing the first and second lines, at least a portion of the first output terminal and at least a portion of the second output terminal are arranged between the first line and the second line for each of the first to Nth terminal pairs, and for the all n, the first switching element and the first diode element which belong to the nth circuit are connected through a first bonding wire, a middle portion of the first bonding wire being connected to the at least a portion of the first output terminal belonging to the nth terminal pair, and the second switching element and the second diode element which belong to the nth circuit are connected through a second bonding wire, a middle portion of the second bonding wire being connected to the at least a portion of the second output terminal belonging to the nth terminal pair.
A second aspect of the present invention is directed to a power module comprising a substrate, first and second power wirings provided over the substrate, first to Nth (Nxe2x89xa72) terminal pairs provided over the substrate, each pair thereof having first and second output terminals, and first to Nth circuits provided over the substrate, each circuit thereof being connected to the first and second power wirings, the nth circuit including, for all n (n=1 to N), a first series circuit having a first switching element connected to the first power wiring and a first diode element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the first output terminal of the nth terminal pair, and a second series circuit having a second diode element connected to the first power wiring and a second switching element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the second output terminal of the nth terminal pair, wherein the first to Nth circuits are arranged in this order, all of switching elements and diode elements connected to the first power wiring are arranged to form a first line, all of switching elements and diode elements connected to the second power wiring are arranged to form a second line aligned with the first line, the switching elements and the diode elements are arranged alternately in all of directions along the first line, along the second line and crossing the first and second lines, at least a portion of the first output terminal and at least a portion of the second output terminal are arranged like a band extended along the first line and the second line therebetween for each of the first to Nth terminal pairs, the second power wiring has a band-shaped portion extended along the first and second lines therebetween, and the band-shaped portion is arranged in parallel with the at least a portion of all of the first and second output terminals.
A third aspect of the present invention is directed to a power module comprising a substrate, first and second power wirings provided over the substrate, first to Nth (Nxe2x89xa72) terminal pairs provided over the substrate, each pair thereof having first and second output terminals, and first to Nth circuits provided over the substrate, each circuit thereof being connected to the first and second power wirings, the nth circuit including, for all n (n=1 to N), a first series circuit having a first switching element connected to the first power wiring and a first diode element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the first output terminal of the nth terminal pair, and a second series circuit having a second diode element connected to the first power wiring and a second switching element connected to the second power wiring which are connected in antiseries, a connecting portion thereof being connected to the second output terminal of the nth terminal pair, wherein the first to Nth circuits are arranged in this order, all of switching elements and diode elements connected to the first power wiring are arranged to form a first line, all of switching elements and diode elements connected to the second power wiring are arranged to form a second line aligned with the first line, the switching elements and the diode elements are arranged alternately in all of directions along the first line, along the second line and crossing the first and second lines, at least a portion of the first output terminal and at least a portion of the second output terminal are arranged like a band extended along the first line and the second line therebetween for each of the first to Nth terminal pairs, the second power wiring has a band-shaped portion extended along the first and second lines therebetween, and the band-shaped portion and the at least a portion of all the first and second output terminals are separately provided on one of main surfaces of a band-shaped insulating layer and the other of the main surfaces, and thereby being opposite to each other in parallel with the insulating layer interposed therebetween.
A fourth aspect of the present invention is directed to the power module according to the second or third aspect of the present invention, wherein the second power wiring has N protrusions protruded from the band-shaped portion to enter the second line, each of the N protrusions being provided between the first diode element and the second switching element which belong to the same circuit and being connected to a middle portion of a bonding wire connecting the first diode element and the second switching element.
A fifth aspect of the present invention is directed to the power module according to any of the first to fourth aspects of the present invention, wherein the first power wiring is provided like a band along the first line, and the first switching element and the second diode element which belong to each of the first to Nth circuits are provided on the first power wiring.
A sixth aspect of the present invention is directed to the power module according to any of the first to fifth aspects of the present invention, further comprising a case for housing the first to Nth circuits provided over the substrate cooperating with the substrate, each of the first and second output terminals of each of the first to Nth terminal pairs having a protrusion which is different from the at least a portion and protruded outward from the case, and all of the protrusions belonging to the first to Nth terminal pairs being provided closer in the same terminal pair than between different terminal pairs.
A seventh aspect of the present invention is directed to the power module according to the sixth aspect of the present invention, wherein each of the first and second output terminals belonging to each of the first to Nth terminal pairs has first and second band-shaped portions having one ends crossing at a right angle to take an L-shaped planar outline, the first band-shaped portion being provided in parallel with the first and second lines corresponding to the at least a portion and an end of the second band-shaped portion corresponding to the protrusion, and the second band-shaped portions of the first and second output terminals belonging to each of the first to Nth terminal pairs are arranged in parallel such that both of the first and second output terminals take an almost T-shaped planar outline.
An eighth aspect of the present invention is directed to the power module according to the seventh aspect of the present invention, wherein the second band-shaped portions of the first and second output terminals belonging to each of the first to Nth terminal pairs are electrically connected through a bonding wire.
A ninth aspect of the present invention is directed to the power module according to the seventh aspect of the present invention, wherein the protrusions of the first and second output terminals belonging to each of the first to Nth terminal pairs are electrically connected through a conductive connecting member.
A tenth aspect of the present invention is directed to the power module according to the seventh aspect of the present invention, wherein the second band-shaped portions of the first and second output terminals belonging to each of the first to Nth terminal pairs are connected integrally with each other such that both of the first and second output terminals take a T-shaped planar outline.
According to the first aspect of the present invention, the elements to be connected to the first power wiring are provided along the first line, the elements to be connected to the second power wiring are provided along the second line aligned with the first line, and at least portions of respective output terminals are provided therebetween. Therefore, the size of the module can be reduced. In addition, the switching elements and the diode elements are provided alternately. Consequently, mutual heat interference of the switching elements, which generate large heat, can be reduced. Furthermore, the bonding wire connecting the element provided on the first line and the element provided on the second line is relayed by at least a portion of the output terminal positioned therebetween. Therefore, wire bonding can be carried out continuously in a manufacturing process and a manufacturing efficiency can be enhanced.
According to the second aspect of the present invention, the elements to be connected to the first power wiring are provided along the first line, the elements to be connected to the second power wiring are provided along the second line aligned with the first line, and at least portions of respective output terminals are provided therebetween. Therefore, the size of the module can be reduced. In addition, the switching elements and the diode elements are provided alternately. Consequently, mutual heat interference of the switching elements, which generate large heat, can be reduced. Furthermore, the band-shaped portion of the second power wiring and at least portions of respective output terminals are arranged in parallel with each other between the first and second lines. Therefore, it is possible to reduce an inductance generated on a current path.
According to the third aspect of the present invention, the elements to be connected to the first power wiring are provided along the first line, the elements to be connected to the second power wiring are provided along the second line aligned with the first line, and at least portions of respective output terminals are provided therebetween. Therefore, the size of the module can be reduced. In addition, the switching elements and the diode elements are provided alternately. Consequently, mutual heat interference of the switching elements, which generate large heat, can be reduced. Furthermore, the band-shaped portion of the second power wiring and at least portions of respective output terminals are provided opposite to each other between the first and second lines with the insulating layer interposed therebetween. Therefore, it is possible to reduce an inductance generated on a current path. In addition, it is possible to decrease the area of the substrate and to further reduce the size of the module.
According to the fourth aspect of the present invention, the second power wiring has the protrusions, and the bonding wire connecting the first diode element and the second switching element which belong to the same circuit is relayed by the protrusion positioned therebetween. Therefore, wire bonding can be carried out continuously in a manufacturing process and a manufacturing efficiency can be enhanced.
According to the fifth aspect of the present invention, the first power wiring is provided like a band along the first line and the elements to be arranged along the first line is provided on the first power wiring. Therefore, the shortest current path is formed between the first power line and each element and an inductance generated on the current path can further be reduced.
According to the sixth aspect of the present invention, portions of respective output terminals are protruded outward from the case, and the protrusions are provided apart between different circuits and close in the same circuit. Therefore, a set of output terminals belonging to the same circuit can easily be connected on the outside. Consequently, the power module can be used for driving an induction motor, a DC motor or the like. In other words, it is possible to implement a power module having high versatility which is not restricted to the use for driving an SR motor.
According to the seventh aspect of the present invention, all the first and second output terminals are L-shaped and the first and second output terminals belonging to the same circuit are provided to take an almost T-shaped planar outline. Therefore, an inductance generated on a current path can further be reduced. Moreover, since the shapes of all the output terminals are L-shaped, all the output terminals can be manufactured by using a single metal mold and a manufacturing cost can be reduced.
According to the eighth aspect of the present invention, the second band-shaped portions of the first and second output terminals belonging to the same circuit are electrically connected through the bonding wire. Therefore, the power module can be used for driving an induction motor, a DC motor or the like. Moreover, the power module is used for driving an SR motor as it is, except for the bonding wire. Consequently, a manufacturing cost can be reduced.
According to the ninth aspect of the present invention, the protrusions of the first and second output terminals belonging to the same circuit are electrically connected to each other through the conductive connecting member. Therefore, the power module can be used for driving an induction motor, a DC motor or the like. Moreover, the power module is used for driving an SR motor as it is, except for the connecting member. Consequently, a manufacturing cost can be reduced. Furthermore, since the connecting member is applied on the outside of the case, a user can manually carry out remodeling easily.
According to the tenth aspect of the present invention, both of the first and second output terminals belonging to the same circuit are connected integrally to take a T-shaped planar outline. Therefore, the power module can be used for driving an induction motor, a DC motor or the like. Moreover, the power module is used for driving an SR motor as it is, except for the output terminal. Consequently, a manufacturing cost can be reduced.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.